Rats that are permanently implanted with chronic intravenous or intragastric cannulae for drug administration and EEG and EMG electrodes for continuous recordings of electrical activities will be used in comparative studies of the EEG and behavioral effects of LAAM, NLAAM, DNLAAM, and methadone. Comparisons will be made of spontaneous vs. naloxone-induced abstinence in rats made dependent by administration of LAAM, NLAAM, DNLAAM, and methadone. Tendencies of LAAM postaddict rats to relapse to morphine, methadone, or LAAM self-administration will be assessed. These findings will be contrasted with morphine or methadone postaddicts relapsing to morphine or methadone self-administration. Protracted abstinence and long-term effects in LAAM-dependent rats following withdrawal will be studied using EEG spectral analysis. Comparative studies of the EEG and behavioral changes and pattern of distribution of self-injections during oral self-administration of LAAM and methadone will be made.